Overview
This lecture covers the fundamentals of communication systems and computer networking for ICT, including definitions, modes, media, protocols, data measurement, transmission methods, network devices, and topologies for exams.
Communication System Basics
- A communication system transfers data from sender to recipient via a specific medium.
- Essential components: sender, recipient, information, medium, and protocols (rules for communication).
- Protocols like HTTP and HTTPS define communication rules; HTTPS is the secure version.
Data Measurement & Units
- Data is measured in bits (b) and bytes (B), where 1 byte = 8 bits.
- Storage conversion: 1 kilobit (Kb) = 1024 bits, 1 kilobyte (KB) = 1024 bytes, 1 megabit (Mb) = 1024 Kb, 1 gigabit (Gb) = 1024 Mb.
- For storage: multiply by 1024; for speed: multiply by 1000.
- Data transfer speed is measured in bits per second (bps).
Data Transmission Modes & Methods
- Transmission modes by direction: simplex (one-way), half-duplex (two-way, not simultaneous), duplex/full-duplex (two-way, simultaneous).
- Distribution modes: unicast (one-to-one), multicast (one-to-few), broadcast (one-to-all).
- Methods: serial (bit by bit, slower, long distance, low cost), parallel (multiple bits, faster, short distance, higher cost).
- Serial transmission types: asynchronous (character-by-character, less efficient), synchronous (block-by-block, more efficient), isochronous (real-time, low delay).
Communication Media
- Wired media: twisted pair (short, EMI-prone, low cost), coaxial cable (moderate distance, EMI shielded), fiber optic (long distance, high speed, expensive, uses light).
- Wireless media: radio waves (long distance, low frequency), microwaves (medium distance, high frequency, line-of-sight), infrared (short range, high frequency, obstacle-sensitive).
Networking & Devices
- Networks: connect multiple computers to share resources and data.
- Types: private (individual/organization-owned), public (government-owned), peer-to-peer (equal nodes), client-server (dedicated server).
- Network devices: modem (digital↔analog conversion), NIC (connects computer to network), repeater (amplifies signals), hub (broadcasts to all), switch (sends to intended device), bridge (connects LANs), router (connects same IP networks), gateway (connects different IP networks).
Network Topologies
- Bus: all devices connected to a backbone, low cost, high collision, easy to add devices.
- Ring: devices in a circle, single path, one device failure affects all.
- Star: central node (hub/switch), high speed, expensive, robust to single device failure.
- Mesh: all devices interconnected, very high speed and reliability, very high cost.
- Hybrid: combines features of other topologies (often tree structure).
Emerging Concepts
- Cloud computing: using remote computers via the internet; scalable, on-demand, pay-per-use.
- Mobile communication generations: 1G (analog, no roaming), 2G (digital, SMS, internet), 3G (e-commerce), 4G (IP-based), 5G (high-speed media).
Key Terms & Definitions
- Protocol — Set of rules for data exchange in communication systems.
- Bit (b) — Smallest unit of data.
- Byte (B) — 8 bits.
- Bandwidth — Maximum data transfer rate of a medium.
- Simplex — One-way communication.
- Duplex — Two-way, simultaneous communication.
- Serial Transmission — Data sent one bit at a time.
- Parallel Transmission — Multiple bits sent at once.
- Modem — Device that converts digital signals to analog and vice versa.
- Topology — Physical or logical layout of a network.
Action Items / Next Steps
- Practice MCQs on protocols, units, and topologies.
- Review conversions between bits, bytes, and their multiples.
- Draw and label diagrams of network topologies and cables.
- Answer: 5 GB equals how many kilobits? (Calculate for homework)
- Comment answers to the provided example problems.